linux-phytec-ti

MAINTAINERS: AVS is not maintained via power supply tree

The adaptive voltage scaling framework is not maintained
via the power supply tree and has its own entry in the
MAINTAINERS file, so add an exception in the power supply
entry.

Signed-off-by: Sebastian Reichel <sre@kernel.org>
Acked-by: Kevin Hilman <khilman@linaro.org>